Numerical and Observational Studies of Tornadic Supercells

虽然在过去的十年里，人们在了解龙卷风及其母风暴的动力学方面取得了进展，但关于导致龙卷风发生的因素以及控制任何给定龙卷风的强度和寿命的因素，人们仍然知之甚少。在这项研究中，首席研究员将研究大尺度环境条件（如风切变和浮力）如何控制超级单体雷暴中龙卷风的强度和寿命。这项工作建立在首席研究员之前对超级单体雷暴中低层旋转发展和龙卷风成因的研究的基础上，是一个合乎逻辑的后续。将进行两个独立的研究方向。首先，首席研究员目前的研究将扩展到龙卷风规模，以努力推进对龙卷风形成的理解。先前的工作已经导致了Rotunno和Klemp范式对超级细胞低级旋转起源的改进。该新理论论证了入流环境的近地面水平涡度对中气旋形成的动力作用，并可用于预测近地面垂直风切变廓线，这是超级单体内产生强低层中气旋的最佳条件。这项工作的扩展包括检查龙卷风尺度的环流是否与中气旋环流直接相关，以及研究剪切和浮力在确定龙卷风产生所需的低层环流和辐合的空间尺度和强度方面的作用。其次，将尝试明确模拟在龙卷风实验中旋转起源验证中观测到的特定超级单体和龙卷风。这部分研究将对云模拟现实主义的现状提供一个急需的评估，并有希望确定对流尺度建模需要改进的具体方面。这项研究的潜在好处有很多。除了增加对风暴和龙卷风动力学的基本了解外，操作界将从这项研究中受益。了解风切变、温度和湿度的哪些特定环境剖面最有利于龙卷风的形成，将使预报员能够精确定位并关注有利于形成强烈龙卷风风暴的小区域。通过更全面地了解与这些超级单体及其龙卷风相关的动力学，改进的恶劣天气预报和多普勒雷达观测可以更有效地用于预测和探测龙卷风的形成并向公众发出警告。＊＊＊

9707815 Wicker While progress has been made over the last decade on understanding the dynamics of tornadoes and their parent storms, much is still unknown concerning the factors that cause tornado genesis and that control the intensity and longevity of any given tornado. In this research, the Principal Investigator will investigate how the large scale environment conditions (e.g. wind shear and buoyancy) control the intensity and longevity of tornadoes within supercell thunderstorms. This work builds on and is a logical follow-up to the Principal Investigator's previous research on the development of low-level rotation and tornado genesis within supercell thunderstorms. Two separate lines of research will be pursued. First, the Principal Investigator's current research will be extended down to the tornado scale in an effort to advance understanding of tornadogenesis. The previous work has resulted in refinements to the Rotunno and Klemp paradigm for origins of low-level rotation in supercells. The Principal Investigator s new theory demonstrates the dynamical role the inflow environment's near-surface horizontal vorticity has on mesocyclogenesis and can be used to predict the near-surface vertical wind shear profiles which are optimal for the generation of strong low-level mesocyclones within supercells. Extension of this work includes examining whether tornado-scale circulations are directly related to the mesocyclone circulation, as well as a study to understanding the role of shear and buoyancy in determining the spatial scales and magnitude of the low-level circulation and convergence needed for the generation of tornadoes. Second, an attempt will be made to explicitly model a particular supercell and tornado observed during the Verification of Origins of Rotation in Tornadoes Experiment. This part of the study will provide a much needed evaluation of the current state of cloud simulation realism and hopefully identif y specific aspects of convective scale modeling which need to be improved. Potential benefits from this research are many. Aside from increasing basic understanding of storm and tornado dynamics, the operational community will benefit from this research. Understanding which particular environmental profiles of wind shear, temperature and moisture that are most conducive for tornadoes will enable operational forecasters to pinpoint and focus on small regions where the conditions are favorble for the formation of intense tornadic storms. By more fully understanding the dynamics associated with these supercells and their tornadoes, improved severe weather forecasts and Doppler radar observations can then be used more effectively to forecast and detect tornado formation and warn the public. ***